The invention concerns an assembly comprising a bearing and a mechanical interface, a braking assembly comprising such an assembly, and an application of these braking assemblies to measuring the torque and the forces applied to one or each of the wheels of a vehicle and to the regulation of at least one control of the vehicle.
Bearings are already known of the type comprising a fixed raceway intended to be associated with a fixed structure, a rotating raceway intended to be associated with a rotating member, and rolling bodies disposed between them.
When it is wished to know forces applied by the fixed structure to the rotating structure, it is known that attached parts forming measuring units can be disposed at the connection between the fixed raceway and the fixed structure.
The document EP-A-0 432 122 illustrates this technology, providing a measuring unit rigidly fixed to the fixed raceway, this measuring unit comprising an annular support and a plurality of sensors associated with the support in predetermined orientations with respect to the axis of rotation.
This type of technology has a certain number of drawbacks.
This is because the presence and multiplicity of the attached measuring units make assembly of the bearing tricky and complex.
The fixed raceway, by trapping the measuring units when the bearing is assembled, subjects them to prestressing which is detrimental to the subsequent measurements of forces.
Moreover, when it is wished also to know the braking torque applied to a wheel by means of a brake calliper, this type of technology cannot be envisaged.
The invention therefore aims to remedy these drawbacks by proposing an assembly comprising a bearing and an interface intended to be interposed between the fixed raceway of the bearing and the fixed structure, the said interface comprising, in an integrated fashion, deformation zones instrumented by means of sensors, and which makes it possible to measure both the forces resulting from the static and dynamic behaviour of the vehicle and the braking torque exerted on a wheel of the vehicle.
To this end, and according to a first aspect, the invention proposes an assembly comprising:
a bearing of the type comprising a fixed raceway intended to be associated with a fixed structure, a rotating raceway intended to be associated with a rotating member, and rolling bodies between them; and
a mechanical interface associated with the said fixed raceway by means of association means, this interface being intended to be interposed between the fixed raceway of the bearing and the fixed structure, the said interface comprising:
first means of fixing to the fixed structure;
second means of fixing a device intended to apply a force to the rotating member; and
at least one elastic deformation zone able to be deformed under the action of forces exerted on the said assembly, at least one sensor able to measure the said forces being functionally associated with the said elastic deformation zone.
According to one embodiment, the interface comprises two flat faces extending radially and connected together by a circumferential face, a bore with a diameter substantially greater than the outside diameter of the fixed raceway being formed in the said interface.
The interface can then comprise first radial projections in which axial holes are formed for fixing the assembly by screwing onto the fixed structure, two adjacent projections being separated by a zone with a lesser axial and/or radial dimension forming an elastic deformation zone, on which the sensor or sensors are disposed.
According to one embodiment, the interface comprises four first projections disposed substantially at 90xc2x0 with respect to each other, defining between them four elastic deformation zones on each of which at least one sensor is disposed.
The interface can comprise second radial projections forming second means of fixing to the bearing the device intended to apply a force to a rotating part associated with the rotating raceway, the projections comprising a base zone and an end zone.
According to one embodiment, the second projections comprise axial holes for fixing the said device by screwing, located in the end zone, at least one sensor being disposed on or in the vicinity of the base zone, this forming an elastic deformation zone.
Two sensors can then be disposed on the circumferential face, on each side of each projection and/or at least one sensor can be disposed on one of the flat faces.
A radial dimension of the second projections can be greater than a radial dimension of the first projections.
According to one embodiment, the interface comprises:
four first projections disposed substantially at 90xc2x0 with respect to each other, defining between them three elastic deformation zones on each of which at least one sensor is disposed; and
two second projections located between two adjacent first projections, each second projection being provided with at least one sensor.
As a variant, openings are formed in the first and/or second projections, sensors being disposed on the internal faces of the openings.
According to a first embodiment, the first fixing means also form means of associating the interface with the fixed raceway of the bearing.
In a variant, the fixed raceway comprises a flange comprising radial projections in which axial holes are formed, disposed opposite those of the first fixing means so as to provide the fixing of the interface by screwing onto the bearing.
According to a second embodiment, the means of associating the interface on the bearing are distinct from the first and second fixing means.
In a variant, the fixed raceway comprises a radial flange, axial holes being formed opposite the said flange and in the interface so as to provide their association by screwing.
According to one embodiment, the elastic deformation zone or zones are located in the vicinity of the first and/or second fixing means and/or in the vicinity of the association means, the sensor or sensors located in the vicinity of the first fixing means and/or in the vicinity of the association means are then arranged so as to measure the forces applied to the first fixing means and/or transmitted to the fixed raceway, as well as their respective movements, in three orthogonal directions forming together a trihedron.
In a variant, the sensor or sensors located in the vicinity of the second fixing means are arranged so as to measure the forces applied to the second fixing means, as well as their respective movements, in three orthogonal directions forming together a trihedron.
The sensors can be or comprise:
strain gauges based on piezoresistive elements;
acoustic surface wave sensors;
magnetic field sensors.
According to one embodiment, at least one sensor is disposed on an intermediate part fixed to an elastic deformation zone by embedding, welding, adhesive bonding or the like.
According to a second aspect, the invention concerns a braking assembly comprising an assembly as described above and a brake calliper associated with the mechanical interface by means of the second fixing means, the so-called calliper being separate from the fixed structure.
The braking assembly can also comprise a brake disc associated with the rotating raceway, inserted between the jaws of the calliper so that this applies a braking force to it by bringing the jaws together.
According to a third aspect, the invention concerns an application of such assemblies to the measurement on the one hand of the braking torque of a vehicle and on the other hand the longitudinal, transverse and vertical forces exerted on one or each of its wheels, in which an assembly is associated with one or each of the wheels, the torque being measured by means of the sensors located in the vicinity of the second fixing means and/or in the vicinity of the association means and the forces by means of the sensors located in the vicinity of the first fixing means.
According to one embodiment, a control device collects the measurements of the braking torque and/or of the forces exerted on the wheels, this device being arranged so as to regulate at least one dynamic control of the vehicle, notably the braking, the acceleration, the steering or the suspension as a function of the said measurements.